Presently, in 3GPP RAN LTE (Long Term Evolution) in uplink, single carrier transmission is gaining attention to achieve a low PAPR (Peak to Average Power Ratio). Further, studies are conducted for a scheme to perform “adaptive modulation (AMC: Adaptive Modulation and Coding)” for selecting a user-specific MCS (Modulation and Coding Scheme) pattern according to a CQI (Channel Quality Indicator) of users to achieve high throughput.
Further, to adopt adaptive modulation and hybrid ARQ to a downlink data channel, in uplink channel, downlink CQI information and downlink ACK/NACK information are transmitted in a control channel.
FIG. 1 shows an MCS table a terminal uses for adaptive modulation for a data channel and so on (hereinafter, “CQI table”) (see, for example, Non-Patent Document 1). Here shows, based on a CQI value, that is, based on channel quality information including an SNR, various modulation schemes and coding rates are read from the table shown in FIG. 1 to determine an MCS for a data channel.
Further, studies are underway to transmit an uplink data channel and an uplink control channel in the same frame, and, furthermore, to determine an MCS for the control channel at the same time as an MCS for the data channel, using a CQI determining the MCS for the data channel (see, for example, Non-Patent Document 2).
Accordingly, similar to the MCS for a control channel, various modulation schemes and coding rates (hereinafter SE: Spectral Efficiency, and SE is defined as the number of bits per symbol×coding rate) are determined in accordance with CQIs. FIG. 2 shows a concrete example of a CQI table in which associations between data channel SE and control channel SE are shown. Hybrid ARQ is not adopted to this control channel. Accordingly, control channel SE is set up robust with respect to CQIs that is, the SE is set up to be low such that required quality is satisfied even in a poor reception environment.    Non-Patent Document 1: R1-073344, Nokia, “Update to 64QAM CQI tables,” 3GPP TSG RAN WG1 Meeting #50, Athens, Greece, Aug. 20-24, 2007    Non-Patent Document 2: 3GPP TS36.212 V8.0.0